The proposed project will evaluate the modification by drugs of the psychological and neurohumoral responses to oral surgery in man. This investigation will be conducted in conscious patients undergoing a minor surgical procedure, the removal of impacted third molars. The three independent variables, anticipatory anxiety, surgical stress and postoperative pain, will be evaluated by a number of established parallel scales. These tests will be administered during a pre-surgery baseline period, immediately prior to surgery (a situation associated with anticipatory anxiety), during surgery, and again following completion of surgery when postoperative pain has set in. The dependent variables, plasma levels of specific beta-endorphin peptides, catecholamines, and cortisol will be determined in samples collected at the same time periods. Double blind procedures will be used throughout; within and between subject comparisons will be made for each measure. The first study proposed is designed to examine the neurohumoral responses evoked by anxiety experienced in the absence of pain. Perceived anxiety will be varied by the intravenous administration of diazepam (0.4 mg/Kg) which results in near maximal anxiety relief. The particular behavioral and biochemical measures of interest will be those made prior to the onset of intra- or postoperative pain. The second study will be conducted in patients experiencing postoperative pain. In this investigation, groups of patients will receive intravenously either morphine (0.15 mg/kg) to modify pain perception, diazepam (0.4 mg/kg) to alleviate anixety, or dexamethasone (0.15 mg/kg) to prevent the release of pituitary Beta-END peptides. Control patients in both studies will receive saline placebo. The oral surgery model proposed is particularly useful in that predictable and quantifiable patient anxiety and pain result and that both of these perceptions can be selectively modified pharmacologically. Using this approach it is possible to dissociate the anxiety and pain components of patient stress and thereby to evaluate their respective contributions to the neurohumoral responses which accompany stress in humans.